Depression is one of the most prevalent and serious mental health problems facing the nation, with substantial consequences of suffering, social and occupational disability, physical illness, and premature mortality. The proposed study will evaluate a developmental biopsychosocial model for understanding depression occurring in the context of marital discord. Specifically, this diathesis-stress model proposes that one pathway to depression is the occurrence of marital discord (i.e., a proximal social stressor) among a subgroup of individuals (a) whose self-esteem is largely invested in interpersonal relatedness (i.e., who have a sociotropic cognitive-personality style; a distal psychological diathesis), and/or (b) who have hypothalamic-pituitary-adrenal (HPA) axis dysregulation (i.e., who respond to stressful interpersonal events with cortisol hyper-reactivity; a distal biological diathesis). It is further predicted that these psychological and biological diatheses may result, in part, from (c) major loss during childhood (i.e., parental death or divorce; a distal developmental diathesis). Investigating this integrative model should serve not only to further understanding of the development, maintenance, and remission of depression, but may also offer directions for developing methods for the prevention and treatment of depression. To evaluate this developmental biopsychosocial model, a sample of 160 couples will be recruited to participate in a two-panel, multi-method evaluation that will include interview, observational, biological, and questionnaire methods of assessment. A 2 (Depression status, based on symptom severity and DSM-III-R) criteria) x 2 (Discord status) factorial design will be employed to test the hypothesized main and interactive effects of depression and marital discord on (a) negative affect and negative affect reciprocity, (b) sociotropic cognitive-personality style, (c) baseline cortisol and cortisol reactivity, and (d) childhood loss. Spouses will (a) complete measures of depression, marital discord, personality style, and childhood loss; (b) be videotaped as they discuss a pleasant event and attempt to solve two problems in their relationships; and (c) view the videotape and provide a continuous rating of the affect they recall experiencing during the marital conflict (i.e., problem-solving) interactions. Salivary cortisol will be sampled pre-, mid-, and post-conflict interaction and after the video recall. Severity of depression and marital discord will be assessed at 3-, 6-, and 9-months following the initial assessment, and couples will complete the same comprehensive evaluation at a 12-month follow-up. The longitudinal component of the study is designed to evaluate (a) the stability of the biological, psychological, and developmental diatheses (i.e., whether they are trait vs. state markers); and (b) whether change in depression severity is predicted by the interactions between the diatheses (sociotropic cognitive-personality style, cortisol reactivity) measured during the initial assessment and change in marital discord between the two periods.